Environmentally friendly cars (also known as a green car or eco-friendly car), including both hybrid vehicles (HEV) and electric vehicles (EV), are well known. Typically, the HEV uses two or more distinct types of power such as an internal combustion engine and an electric motor, while the EV is propelled by one or more electric motors, using electrical energy stored in rechargeable batteries or other energy storage device. While operating, the HEV can use a generator to make a battery self-powered so that the self-powered battery can supply a power for vehicle operation. Particularly, the HEV can include a regenerative braking system which converts its kinetic energy occurred by a counter-rotating motor into an electric form either used immediately or stored in batteries in order to increase energy efficiency.
Like many electronic devices, the EV is designed to operate after being charged. If infrastructures for charging the EV are not enough, most people can be hard pressed to use the EV. To overcome such issues, a plug-in hybrid electric vehicle (PHEV) has been developed. The PHEV is a hybrid electric vehicle that uses rechargeable batteries, or other energy storage device, that can be recharged by plugging it in to an external source of electric power, usually a normal wall socket, which is distinguishable from conventional hybrid electric vehicles which use a generator to power the electric motor or to recharge the batteries.
Sufficient charging infrastructures may be required to use the PHEV or EV. Also, compatibility between different charging infrastructures a critical requisite to secure E-mobility for EVs. The infrastructure can be required to charge plural types of vehicles. Thus, a standard organization has tried to standardize a method or a technique for charging EVs. For example, in the International Electrotechnical Commission (IEC) which leads standardization for vehicle charging technique, the Technical Committee 69 (TC69) (i.e., Electric Road Vehicles and Electric Industrial Trucks) handles technical issues regarding a charging system, a charging interface, a communication protocol, and the like.
Standardized communication method can be required to secure a customer's safety and provide an effective service. Generally, two methods regarding the communication protocol for charging EVs have been developed. One is a Controller Area Network (CAN) technology used in a quick charging method for battery electric vehicles known as CHAdeMO, and the other is Power Line Communication (PLC) technology used in Combined Charging System (COMBO).
The Power Line Communication (PLC) technology can include a communication technique which transmits a low frequency (e.g., 50/60 Hz) power signal with a high frequency communication signal of dozens to hundreds KHz via a power line/cable. The communication between an electric vehicle and a charging device, which is internationally standardized in the PLC technology, can sequentially proceed with some predetermined procedures which are defined by the standard even if a function achieved by the predetermined procedures are not actually used, because of several reasons such as optional services suggestion, smart grid engagement, and the like. When there are plural charging devices adjacent to an electric vehicle, the electric vehicle may not be able to specify or recognize the charging device connected to the electric vehicle for performing charging operation. Since a single power cable can supply a power to several charging stations, the electric vehicle should recognize which one of charging stations is actually connected to the electric vehicle through a protocol. Unfortunately, another charging station which is not connected to the electric vehicle can respond because of undesired interference. In order to avoid this undesirable situation, the international standard defines a Signal Level Attenuation Characterization (SLAC). However, the described issues above are not completely resolved.